THE BRONX - A Bronx family is trying to come to grips with a second tragic death.One-year-old Christopher Mercedes was killed by the family Jeep on Thursday. Officials say he was accidentally rolled over after his mother thought she put the car in park.One neighbor said the boy's mother was crying and screaming, "Somebody help me, he's all I have." Witnesses tried to save the only child, but were unable to.Christopher Mercedes' father was killed in Iraq in February of last year. The mother was still pregnant with Christopher at the time of her husband's death.